1. Technical Field
The present invention relates to a passive entry system for setting an engine ready for start by transmitting inherent information from a portable unit carried by a driver in a wireless fashion when the portable unit is authenticated as legitimate through authentication by an authentication unit.
2. Related Art
A passive entry system as disclosed, for example, in JP-A-2003-013644 has been known as one of conventional vehicle anti-theft or theft security systems. The passive entry system includes mainly a portable unit adapted to be carried by a driver for transmitting inherent information on a high-frequency radio wave, an authentication unit provided on the vehicle side for receiving a transmission from a transmission unit and authenticating whether or not the portable unit is legitimate and a control unit for supplying power for a predetermined electric component provided on the vehicle so as to set the engine ready for start in the event that the portable unit is authenticated as legitimate through authentication by the authentication unit.
In the configuration, when the driver who carries the portable unit approaches the vehicle, the authentication unit performs an authentication, and power is supplied to the predetermined electric component provided on the vehicle, whereby the engine is set ready for start. Namely, when the portable unit enters a reception enable range of the authentication unit (a range within which a radio wave from the portable unit can reach the authentication unit), power is automatically supplied to the electric component on the vehicle, and the authentication of whether or not the portable unit is legitimate is carried out based on the information sent from the authentication unit, whereby the improvement in operability and theft preventive effectiveness can be realized.
In the above conventional passive entry system, however, when the system is applied to a vehicle in which a filler cap on a fuel tank thereof is opened and closed through a key operation, there has been caused a problem that another separate function becomes necessary in order to maintain the explosion-proof properties of the fuel tank.
Namely, in a vehicle in which the conventional passive entry system is not provided, since when filling a fuel tank on the vehicle, an ignition key inserted in an ignition switch is once withdrawn therefrom to thereby stop the engine and thereafter a filler cap is unlocked with the key, there always exists a mechanism in which when the filler cap is operated with the key, the engine is stopped at all times. In contrast to this, since with the passive entry system, the running state of the engine is maintained only if the driver carries the portable unit, a separate mechanism for stopping the engine is needed when the filler cap is unlocked with the key in an attempt to fill the fuel tank.